eiru_sale_commission/views/res_partner_view.xml

<?xml version="1.0" encoding="utf-8"?>
<openerp>
    <data>

        <record id="view_partner_form_agent" model="ir.ui.view">
            <field name="name">res.partner.form.agent</field>
            <field name="model">res.partner</field>
            <field name="inherit_id" ref="base.view_partner_form" />
            <field name="priority" eval="18"/>
            <field name="groups_id" eval="[(4, ref('base.group_sale_salesman'))]"/>
            <field name="arch" type="xml">
                <xpath expr="//page[@name='sales_purchases']//field[@name='supplier']" position="after">
                    <field name="agent" string="Agent" />
                </xpath>
                <field name="user_id" position="after">
                    <field name="agents"
                           attrs="{'invisible': [('customer', '=', False)]}"
                           widget="many2many_tags"/>
                </field>
                <page name="sales_purchases" position="after">
                    <page name="agent_information"
                          string="Agent information"
                          attrs="{'invisible': [('agent', '=', False)]}">
                        <group>
                            <group>
                                <field name="agent_type"/>
                                <field name="commission"
                                       attrs="{'required': [('agent', '=', True)]}"/>
                            </group>
                        </group>
                    </page>
                </page>
            </field>
        </record>

    </data>
</openerp>